Biodelignification of lemon peels using Aspergillus sp. to improve yield and composition of extxracted lemon oil

Abstract

Lemon oil obtained from lemon peels has a high market value. However, the presence of lignocellulose composed of cellulose, hemicellulose, and lignin, can inhibit the extraction process. This study aimed to determine the effect of biodelignification on lemon peels using Aspergillus sp. towards lignin content, yield, chemical composition, and productivity of lemon oil. A solid-state fermentation was carried out under controlled relative humidity of 99% and a light intensity of ~0 W/cm2 for 0, 3, 6, and 9 days. The number of spores used was in the range of 0.3-5 x 105 spores/gram substrate with a ratio of spore solution and substrate of 1:1. Extraction was performed using a steam distillation method at 97-98°C for 6 hours. The results showed that the lignin content decreased with an increased fermentation time: 8.01%, 6.97-7.28%, 5.83-7.28%, and 4.35-5.44% dry weight for day 0, 3, 6, and 9, respectively. Lemon oil yield increased as the period of fermentation increased up to 0.27%, 0.29-0.31%, 0,30-0.46%%, and 0.67-0.79% for day-0, 3, 6, and 9, respectively. A major component of lemon oil is d-limonene. The d-limonene content reached 72,54% for day-0, 73-99% for day-3, 75,09-84.59% for day-6, and 88,03-99% for day-9.